1. Field of the Invention
The present invention generally relates to a speed control system and method for a watercraft, and more particularly relates to an improved speed control system and method that controls a speed of a watercraft selectively using at least two control modes.
2. Description of Related Art
Computerized controls have become popular in recent years for watercrafts. In one arrangement, a watercraft has a propulsion device that propels the watercraft. Typically, an outboard motor can have such a propulsion device that is powered by an engine. An air intake device for the engine can incorporate a throttle valve unit that has a throttle valve to regulate an amount of air or rate of airflow to the engine and an actuator to actuate the throttle valve. The actuator moves the throttle valve generally between a fully closed position and a fully open position under control of a control device. The engine generates an output in accordance with the open position or open degree of the throttle valve. Normally, the greater the open degree, the higher the rate of airflow and the higher the engine speed. A speed or velocity of the watercraft varies generally in accordance with the engine speed.
A computerized speed control system that has the control device can be applied to the throttle valve unit. The speed control system typically has, for example, a manual control mode and a constant speed mode. In the manual control mode, the throttle valve unit is manually controllable and can be set at any position to vary the speed of the watercraft. In the constant speed mode, the throttle valve unit is automatically held at a certain position to keep the watercraft in a desired and substantially constant speed. A mode selector can be provided to allow the operator to select the manual control mode or the constant speed mode.
The speed control system is convenient for a planing boat used for waterskiing, wake boarding, or hydrosliding. Typically, an operator of the boat accelerates an engine, which is typically incorporated in an outboard motor mounted on the boat, in the manual control mode and brings the boat to a target speed that is suitable for waterskiing, wake board riding, or hydrosliding. The operator then selects the constant speed mode to keep the speed of the boat at the target speed.
Such a computerized speed control system and method is disclosed, for example, in JP2001-152898.
The speed control system is advantageous because the operator does not need to manually adjust the throttle lever to maintain the boat's speed substantially constant. On the other hand, however, the conventional speed control system is sometimes inconvenient. For example, the operator of the watercraft generally must decelerate the boat and circle back when the person being towed falls or releases the tow rope. In order to do so, the operator typically must operate the mode selector to switch to the manual control mode from the constant speed mode. This operation is not only burdensome for the operator but also takes time, causing an undesirable delay before deceleration occurs. This delay may also be problematic in other scenarios in which the operator needs to desires to rapidly adjust the boat's speed.